Feature: keep original file modification or creation date

[woefi]

Some images do not have EXIF dates embedded, so I have to rely on their creation/modification date. When optimizing with ImageOptim (or other sorts of tools) it's always a "new" file with a new date.

I read that some people wrote scripts to:

• first remember the date,
• then use OPTIMIZETOOL to convert,
• then set back the date

Of course, this could be so much nicer, if already implemented in the app, right?

Use cases for me would be:

• Screenshots (obviously no EXIF, and bloated by display color profiles, which I want to get rid of)
• Older Photos (early-digital-era)
• to clean up or slim down Folders of graphic assets without them resurfacing on top as "new"

If someone has an universal script (macOS) for me to achieve this with all sorts of FILETYPE and OPTIMIZETOOL I would be very happy. (for example, I have many old family videos with no EXIF but correct creation dates, which need to get converted to mp4 via handbrake)

[codename-osni]

Same as #133